Recently, chance of getting and reading information of documents and images in a form of electronic information simpler than those in a form of usual printed material on paper is more increased accompanied with increasing in the rapidness of the processing speed of personal computer, spreading of network infrastructure and capacity glowing and cost lowering of data storage.
As the means for reading such the electronic information, liquid crystal displays and CRT are usually used and light emission type displays such as an organic electroluminescent are mainly applied recently. However, it is necessary to observe such the reading means for long time, particularly, when the electronic information is information of documents. Such the action is difficultly considered as a gentle means for the human. As the problems of such the light emission type displays, it has been known that eyes are fatigued by flicker, portability is low, posture for reading is limited and focusing on the still image is necessary and electric consumption is increased accompanied with prolongation of the reading time.
Although memory type reflective displays utilizing outside light which do not consume electric power for sustaining the image have been known as the means for compensating such the defects, such the displays are difficultly considered to have sufficient properties in the present condition by the following reasons.
In the system using a polarizing plate such as a reflective liquid crystal plate, the reflectivity is low as about 40% so that display of white image is insufficiently and majority of the production methods to be used for producing the constituting parts of the display is not always simple is utilized. A polymer dispersion type liquid crystal requires high voltage and the contrast of the obtained image is not insufficient since difference of between the refractive indexes of organic compounds. A polymer network type liquid crystal has problems that high voltage is required and a complex TFT circuit is necessary for improving the memorizing ability. A displaying element using electrophoresis requires high voltage such as 10 V or more and has anxiety about lowering in the durability caused by coagulation of the electrophoresis particles.
An electrochromic displaying element, hereinafter referred to as EC system, or an electro-deposition system, hereinafter referred to as ED system, applying the dissolution-deposition of metal or metal salt has been known as a method for dissolving such the problems of each of the above systems. The EC system has advantages such as that the element can be driven at low voltage such as 3 V or less, the full color image can be displayed, the structure of the cell is simple, and the quality of white image is high. The ED system has advantages such as that the element can be driven at low voltage such as 3 V or less, the structure of the cell is simple, the contrast of black and white in the image is suitable and the quality of black image is high, and various methods are disclosed; cf. Patent Documents 1 to 5, for example.
As a result of detailed investigation on the technology disclosed in the above Patent Documents by the inventors, it is found that an unevenness on the displayed image occurs during repeating use of the prolong time. As means for solving this defect, to utilize high viscosity by gelling a electrolyte or a polymer binder is investigated, however, it is found that by using a gel electrolyte or high viscous electrolyte, general method for producing a display element such as LCD cannot be applied as it is.
For example, in a liquid crystal injection method known as a general method for producing LCD, problems occurs such that long time is needed to injection and an unfilled room remains during injection by using a gel electrolyte or a high viscous electrolyte. A liquid crystal dropping method recently prevailed in method for producing a large size LCD is a proper method to fill a gel electrolyte or a high viscous electrolyte into a cell, however, effective methods for deciding a gap between opposed electrodes cannot be founded. By a method for deciding gap by photo spacer, for example, a high aspect ratio cannot be obtained because of a durability of a spacer. As a result, a problem of lowering an open ratio of a display area remained. Other method comprising steps: mixing spacer which decides a gap in an electrolyte, dropping an electrolyte by dispenser to form electrolyte layer is known. However, it is found that problems of lowering a curing of a sealing agent or lowering an adhesion remained, because an incompletely cured curing agent contacts with an electrolyte layer.
A method for filling an electrolyte having low viscosity into a cell and gelling an electrolyte by cross linking an electrolyte after filling into a cell is disclosed in Patent Document 6.
However, as a result of detailed investigation on the technology disclosed in the above Patent Documents, it is found that there are still problems such that a cross linking is gradually proceeding after producing an element, or display properties vary because of forming byproducts.    Patent Document 1: International Patent No. 2004/068231    Patent Document 2: International Patent No. 2004/067673    Patent Document 3: U.S. Pat. No. 4,240,716    Patent Document 4: Japanese Registration Patent No. 3428603    Patent Document 5: Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP-A) No. 2003-241227    Patent Document 6: Japanese Registration Patent No. 3804822